1. Field of the Invention
The present invention relates to a battery module including a plurality of unit batteries. More particularly, the present invention relates to a battery module having a coolant passage for cooling unit batteries and a gas exhaust passage for exhausting gas generated from the unit batteries.
2. Description of the Related Art
Unlike a primary battery that is incapable of being recharged, a rechargeable battery may be repeatedly charged and discharged. A low capacity rechargeable battery composed of a single cell is generally used for a portable small electronic device, such as a mobile phone, a laptop computer, and a camcorder. A large capacity rechargeable battery composed of a plurality of cells connected in a form of a pack is widely used to drive a motor for a hybrid electric vehicle.
Such rechargeable batteries are serially connected to form a rechargeable battery module to drive a motor for an electric vehicle, which needs a large amount of electric power. In general, a battery module is composed of a plurality of serially connected rechargeable batteries. Hereinafter, the term “rechargeable battery” refers to a unit battery throughout the specification for better understanding and ease of description.
Each unit battery includes an electrode assembly having an anode and a cathode with a separator interposed therebetween, a case having a space for housing the electrode assembly, and a cap assembly coupled to the case for closing and sealing the case and having an electrode terminal electrically connected to the electrode assembly. In general, unit batteries are arranged at regular intervals in a housing and terminals of the unit batteries are connected with each other, thereby forming a battery module.
Since many unit batteries are connected to form one battery module, the battery module must effectively dissipate heat generated from each unit battery. The heat dissipation characteristic of the battery module is very important because the performance of not only the unit batteries but also an electronic device employing the battery module is significantly influenced by the heat dissipation characteristic.
If the heat is not properly dissipated, a large temperature deviation is generated among the unit batteries. Therefore, the battery module may not output sufficient power to drive an electric cleaner, an electric scooter, or a vehicle (e.g., an electric vehicle or a hybrid electric vehicle). If the internal temperature increases by the heat generated from the unit batteries, an abnormal reaction occurs internally. As a result, the charging and discharging performance of the unit batteries is deteriorated.
In addition, gas may be generated in the unit battery while charging and discharging are repeatedly performed. Particularly, since the battery module includes the plurality of unit batteries connected to each other, the gas is required to be quickly and efficiently released. That is, when the gas is not efficiently released, internal pressure increases in the unit battery, and there may be a danger of a rupture or explosion.
However, in conventional battery modules, the heat dissipation and the gas output of the unit battery may not be completely solved. In addition, when a battery module has a configuration for considering the heat dissipation and the gas output in the conventional battery modules, the configuration is complicated or the size of the battery module is problematically increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.